Here's a place where I can post my thoughts on new papers, provide updates on my projects, and post info that will eventually be on my website The Theropod Database - http://theropoddatabase.com/ . It will center on theropods, but may delve into other topics as well such as phylogenetics.

Thursday, November 6, 2014

SVP 2014 Day 1

Hi everyone. Sorry about the lack of posts- coding ornithomimosaurs in the Lori matrix. We'll see where Deinocheirus ends up. Also, that new Erlikosaurus cranial description with fully rotatable 3D elements that you can separate and view any cross section of- coolest theropod osteology ever. Everyone should be doing that with their material. But hey, SVP started. No, I'm not in Berlin, but I figured I'd report on cool theropod abstracts. The embargo states we can't post about them until the talks have been given, and it's now Thursday in Berlin, so let's cover Wednesday's interesting talks and posters.

Dyke et al. are presenting on Balaur being an avialan instead of a dromaeosaurid, which I agree with.

Rauhut and Foth suggest Juravenator has "a number of characters shared with basal theropods, such as the presence of a posterior pleurocoel in the cervical vertebrae, a lateral brevis shelf that is continuous with the supraacetabular crest and a well-developed antitrochanter in the pelvis..." Very interesting. Those are ceratosaur-grade characters, which would make it even more basal than the supposedly megalosauroid Sciurumimus. They say "Recently discovered casts [of the Compsognathus longipes holotype] show that the specimen is better preserved than first described and provide new data on its morphology, indicating that it is not the same taxon as the French Compsognathus." I'd love a redescription since Ostrom's 1978 publication, but I think these Lagerstatten theropods are always oversplit, so color me doubtful. Especially since they say Archaeopteryx "includes probably at least three, and as many as four to five species."

Speaking of which, Kundrat et al. CT scanned the Daiting (8th) Archaeopteryx specimen and found "the internasal and interfrontal sutures are obliterated in the Daiting specimen in contrast to the Eichstätt and Thermopolis specimens which are of similar size. This and numerous other cranial features that distinguish the Daiting specimen from the other specimens of Archaeopteryx suggest that it may represent a new species." We'll have to see what those numerous other features are, and the fact the Daiting specimen is from a younger formation than the others gives some a priori reason to expect a new species, but sutures are often destroyed by taphonomy (e.g. Apsaravis' apparent notarium), so I'll need better evidence than that considering how crushed the skull is.

Lefevre et al. report three new paravian specimens from the Tiaojishan Formation of China, the same formation as Anchiornis, Aurornis, Eosinopteryx and maybe Xiaotingia. All of these emerge as basal Avialae in their analysis, though at least one is stated to have troodontid characters, and we know how easily all of these Tiaojishan taxa switch positions. Interestingly, Eosinopteryx is said to be immature based on histology despite the original description stating "the holotype of Eosinopteryx had reached a late ontogenetic stage (subadult or adult): neurocentral sutures are closed on all exposed vertebrae and the suture between the astragalus–calcaneum complex and the tibia cannot be discerned." I'd caution again that taphonomy can hide sutures, and think that the situation here will prove similar to the Solnhofen one- the specimens will all be different from each other in ways that suggest individual and ontogenetic variation. If not ontogenetic, the plumage variations are bound to be taphonomic. The Lori analyses does suggest one of these taxa is distinct and not what we think it is, but that will have to wait...

Stiegler et al. (with Xu as a coauthor) state "Optimization of manual characters suggests that the manual morphology of Limusaurus is unlikely to be representative of the averostran ancestor as previously hypothesized." Which might translate as 'we were wrong that the reduced manual digit I means tetanurines lost digit I', and yet they say "we argue that the presence of bilateral digit reduction in Limusaurus and other ceratosaurs remains a key piece of evidence for understanding theropod digit homologies." So from the abstract, that sounds like saving face.

Foth et al. say that in Sciurumimus, "Along the dorsal side of the tail the skin is decayed, revealing a horizontal meshwork of thick, short, wrinkly filaments overlain by an outer skin layer. Due to their different morphology and different luminescence, we interpret these filaments as remains of collagen fibers from the dermis, covered by epidermis, rather than as feathers." See, Lingham-Solier- collagen can be preserved, but it's not feathers. Wish the guy would buy a high-resolution camera.

Funston and Currie reveal Elmisaurus rarus has a cranial crest, and agree with me that Leptorhynchos is unnecessary.

Tanaka et al. present a poster on the Japanese hesperornithine. Seems it would fall within Hesperornis sensu lato as far as the Database is concerned.

Dal Sasso et al. present a poster on new cranial remains of Razanandrongobe, which suggest it's a basal mesoeucrocodilian. One more potential theropod down.

Holtz et al. have a poster which includes a new probable Anzu specimen from the Hell Creek of Montana. It "includes distal hindlimb, pelvic elements, dorsal ribs, and caudal vertebra. Given the origination of these bones relative to the local outcrop, it seems quite likely that more the skeleton is preserved and is slated for field recovery." Excellent.

3 comments:

Nice the Limusaurus guys are re-evaluating Limusaurus as not relevant for tetanuran manual homologies, as most of us in the blogosphere have suggested ;-)I'm involved in both Dyke et al. and Lefevre et al. talks and projects: we hope both will be published as actual papers next year. (Fingers crossed)

Stiegler et al. (with Xu as a coauthor) state "Optimization of manual characters suggests that the manual morphology of Limusaurus is unlikely to be representative of the averostran ancestor as previously hypothesized." Which might translate as 'we were wrong that the reduced manual digit I means tetanurines lost digit I', and yet they say "we argue that the presence of bilateral digit reduction in Limusaurus and other ceratosaurs remains a key piece of evidence for understanding theropod digit homologies." So from the abstract, that sounds like saving face.

Unfortunately I missed that talk. Everything interesting at the same time, you know how it is.